The Flash has really hit the ground running — with the events in Tuesday's midseason finale significant enough for the season finales of most shows. Barry (Grant Gustin) faces his arch-nemesis (and mother's killer) Reverse-Flash, while Caitlin (Danielle Panabaker) is confronted with the fact that her fiancé might not actually be dead.

Tuesday's ambitious episode is two minutes longer, and Kreisberg credits The CW for allowing them to tell the story the way The Flash team felt it needed.

"They saw an early cut of the show that was considerably longer and they said they wanted to keep as much as we could," Kreisberg says. "Without generosity and spirit on their part, some of the really special moments would have been lost."